The proposed longitudinal R01 study will elucidate mechanisms underlying the relationship between sleep problems and propensity to drug/alcohol use in adolescents. Many questions remain about this putative relationship given that prospective studies with a pre-drug exposure baseline are few and integrative models are lacking. A systems approach is needed that examines the inherent linkages, temporal dynamics, and mechanisms in the relationship between sleep disturbances and drug abuse. Our integrative, temporal model theorizes that sleep problems will be significant predictors of drug/alcohol initiation and escalation of use in adolescents. We propose further that this relationship can be explained at least in part by emotion dysregulation, as measured by tasks that recruit affective limbic structures and perturbations in neuroendocrine (cortisol) functioning Level of cognitive functioning, which is affected by sleep problems and stress and is associated with emotional dysregulation and risk for drug abuse, will moderate the relationship between sleep problems and drug use. Exposure to prolonged stress (e.g., maltreatment, neglect, divorce, poverty), is expected to amplify the mediational relationship because it has been shown to induce emotion dysregulation, disrupt sleep, and influence drug abuse risk and relapse. Gender and pubertal development also will be included in these models, given findings that sleep problems are reportedly more predictive of drug use initiation in boys than in girls, and that pubertal development in both sexes is associated with poorer sleep quality and duration. Finally, the model predicts that eventual drug use will exacerbate sleep problems and lead to further decrements in sleep, emotion regulation, and cognition, promoting an escalating pattern of use. We have a unique opportunity to study these relationships by accessing participants (529 parent-child dyads) in an unprecedented ongoing longitudinal, prospective study of drug use (with a focus on marijuana, the most commonly used illicit drug in adolescence) use in a community with a high prevalence of use. Baseline data were collected when youth were aged 10-12 and the last wave of data collection is near completion with youth between 12-14.5 years old. The funded study was designed to identify the neurocognitive precursors and consequences of marijuana use relative to other drug and nonuse trajectories. The children are being assessed using measures of lifetime stress exposures, sleep habits and problems, IQ, ECF, emotion regulation, behavioral problems, psychiatric disorders, and drug/alcohol use (only youth drug and alcohol nave at baseline were included). The proposed study would prolong data collection for two additional 28 month waves into later adolescent years (until ~18-20 years old) when pathways of drug use become increasingly clear, transitions to an escalated pattern of use have surfaced, and consequences of use become apparent. To test the proposed hypotheses, we will add cortisol sampling, sleep log, sleep actigraphy, and parent questions regarding the child's sleep patterns. If sleep problems in childhood indeed increase the probability of onset of drug use and treatment intractability, greater attention by parents, teachers, and clinicians to the underlying causes of sleep problems in children and adolescents would have significant preventive and/or ameliorative long-term implications given the malleability of these functions.